the one with more similarities would be that you would have asked the dealer to sell at $28k, the dealer says $30k and you say okay.

secondly the courts accept verbal contracts unless there is a statutory carveout for a specific kind of agreement, the courts require proof to rule which verbal contracts happen to lack. so if you did it over email, or did it through a broker's portal that says using it is a binding contract, then a court would have the proof, which is the logic of the actual case here.